Joseph becker



Sept. 13, 1932. J. BECKER nIsTILLATIoN oF TAR Filed April 17. 1928 INVENTOR. Josep/7 ecker? vQMATTOR/x Y www Nm Patented Sept. 13, 1932 UNITED.STATES JosEPH BECKER,v oF vonnrmv Tow-Nsmr, ALLEGHENYiooUNTY., PENNSYLVANIA, As-

sIGNoR To mnnxorrncas COMPANY or DELAWARE, A CORPORATION 0F DELL WARE Appiication niet Apriri'z,

The distillation vof tar the presence of -a flowing gas suchy vasv steam, flue gas, nitro- -gen and even air, iskn'ovvnland has been resorted to for `the purpose of producing the Vdecomposition or cracking vof the distillates evolved, to increasethe yield of such' distillates and for other reasons. vIt is highly desirable that gas used for this purpose .be inert with respect to the tar constituents and.

distillates, i. e., that it containno freeoxygen.

lnV general, prior attempts along this line Vhave involved `recirculation of the gas. In such recirculation systems, lthe recirculated gas must be indirectly heated, Which involves certain losses and has not .always accomplished the desired result in that it has been di'icult to carry the distillation fa-r .enough to produce pitch residues of highmelting points, especially` when 'nof other means of heating tar has been provided.

Flue gases as used in the prior art have, on the other hand, contained appreciable amounts of free oXygen,rendering .them unsuitable for use Without recirculation. Moreover, the flame temperatures attained When gas is used as fuel are too high to permit .the

35 products of 'combustion to be used for kthe purpose in vieW Without deleterious effect.

It has also been proposed to employ the sensible heat ofcoke-oven 'gases leaving the distillation apparatusasa means for distilling tar, but tar distillation effected on top of or in close proximity to the'cokingfretort ovens themselves is attended With numerous inconveniences and difficulties," as Well ascertain heat losses that may dissipate any advant-ages obtained in this manner. v This is particularly true when it is attempted to .obtain pitch residues from the distillation process vvhich'have very highvmeltingpoints-and which are suitable for'coking.

An object of the present .invention is `to 1928. Serial No.v1270,646.

provide aV process of distilling prior art.

tar .that shall be .free lof most of the disavantages of the` A second object ofthe present invention is My invention has for further objects suchv other operative :advantages and results Vals v.may hereinafter be found to obtain.

According to the process .of my invention, I burn gaseous fuel, preferably a portion of ,the fuel gas to be supplied :to a 'battery of ,coking retort ovens, and' add further amounts rvofcombustible gas thereto before contact with .the itar to be distilled under conditions that -Willfinsure the elimination of free oxygen from the gas stream, and `produce la gas of large volume and proper temperature lfor :tar

distillation o Ibring ,-a gas mixture prepared in the fmanner that will be specified herein into contact With the tar .to be distilledin suitablercontact apparatus and preferably with counter-,current flow of the tar `being .dis-

tilled and the gases used as distillation medium. 1- Y The gases escaping from the contact -ap- .paratus lare thencooled tocondense vtar dis- :tillates and are'used yfor combustion purposes for which they are suitable, for eX- lample, they may vbe used for lheating the coking retort ovens, either alone o r mixed with further fuel gas. f

IPreferably a lportion of :the Vfuel gas *for the carbonizing apparatus is usedito distill Ythe vcoal tar ,separated from the coal gas liberated in said carbonizingapparatus :but

other and additional tar, such as Water-gas tar `ortar from other and lindependent yGarbonizing apparatus kmay lalso bedistilled in thesame manner andk in tthe same distillation.

lmay be supplied to the While the heat required for the distillation of the tar is preferably obtained by burning some of the coal gas produced in the coking retort ovens to which the invention is applied, it may also be obtained from other fuel gas, such as producer gas, blue gas or-blast furnace gas, which is used as fuel for heating the coking retort ovens.

ln order that my invention may be clearly setfforthl and understood, I now describe lwith reference to the accompanying drawing a preferred manner in which it may be practiced and embodied but without limiting my invention to this illustrative instance. l

The single figure of the drawing is an elevational view, parts being shown sectionally and more or less diagrammatioally of a coal gas plant and including means for distilling tar. f c

In this instance, coal gas is produced by the distillation of carbonaceous material such as. coal in a battery -ofcoking retortovens l. The gases liberated'during the carbonization of the coal escape through an oiftake pipe 2 into acollecting main 3 and are conveyed through a suction main 4 in which there'is provided a pitch trap 5 to a primary cooler G.' The gases then pass through a further section of the suction main 4 to an exhauster 7 and are drawn into a pressure main 8, passinginsuccession through a tar extractor 9, an ammonia saturator 10, an acid separator 11 and afinal cooler 13, which are located along the pressure main 8.

The various devices and functions performed thereby are too well known in the coal-gas art to require detaileddescription. Separation of tar occurs in the pitch trap 5, the primary cooler 6 and the tar extractor 9, and the tar separated in these devices is allowed to drain through lines 14, 15 and 16, respectively,into a hot drain tank 17.

rlhe exhauster 7 may also serve to remove 'considerable amounts of tar and this tar is also conveyed to the hot drain tank 17. `The tar collecting in thevhot drain tank 17 is removed through a line 13 and passes to a separating tank 19 where any entrained ammoniacal liquor is separated therefrom.

The ammoniacal liquor escapes from the Y separating tank 19 through a line 20 and the tar passes through an overflow 21 int-o a storage tank 22 where it is held and from which it is released for distillation, as will be shown below. Additional tar from other sources storage tank 22 through a line 23.

The' pressure main 8 beyond the final cooler 13 divides into a branch 24 that is provided with a valve 25 and into a branch I26 leading to a fuel gas holder 27. The surplus gas not required for underiiring the coking retort ovens 1 is withdrawn through the main 24 and only` the fuel gas required for underfir- `ing the oven which may amountto from about tar.

Lampe/i.

`When dehydration is not required, valve 33 isclosedand valve 37 is opened and the tar 'passes lfrom the line 31 through the line 34 into the upperspart of the contact device 30. The tar passes downwardly through the contact device yin Vfinely divided form.

. TheV contact. device 30 is provided with anV adjoining furnace 4() having two main compartments 41 and 42. A portion of the fuel gas withdrawn from the fuel gas holder 27 through a` main 43 is introduced through a line 44'having avalve 45 and a burner y46 into the combustion space 41 of the furnace 40.

This portionof the fuel gas is burned preferably under conditions which promote complete c-ombustion, andthe products of combustion pass into the compartment 42 where they are augmented by further amounts of gas withdrawn from the main 43 through a branch 47 having a valve 48.

. Preferablyenough additional gas is supplied through the main 47 to reduce the temperatureof the mixed combustible gas and products of combustion to below about 1400O F. and conditions are so regulated that any appreciable amounts of free oxygen in the products of combustion of the gas burned in the campartment 41 are caused to combine Y with somey of the unburned gas introduced to the compartment 42 through the main 47.

. The mixed gas passes from the furnace to the contact apparatus 30 and passes upward in counter-current to the descending During the Contact of the hot gases, the tar distillation of the latter is effected and a pitch residue is removed from the bottom of the Contact device4 30 ythrough a line 49 leading to a collector 50 of suitable design.

During Vthe distillation, tar distillates are evolved and these mingle with the gaseous heating fluid and pass with it from the contact apparatus 30 through a line 51.

A cyclone separator52is placed in the line 51 for the purpose of removing tar entrainedv by the gas and of preventing such tar from being carried into the condensing apparatus. Other devices may be substituted for the cyclone separator 52., such, for example as, an electrical Vprecipitator or other device; rl`he tar separated from the may be led back into the distilling apparatus.

It will be apparent that, when the distilla tion of tar is conducted in'thismanner, the gases vescaping fromy the separating device lli) 52 will contain tar distillates of a considerable" range. For this reason, fractional condensation of these distillates is to be preferred.

. In the present instance, the gases pass to a condenser 53 that isconstituted ofA afplurali'ty of alternate cooling sections 54 that may consist of chambers provided with aplurality of tubes wherein is circulated a cooling fluid and of fractionating sections 55 which arepreferably of the well-known bell-and-tray type.

The temperatures through the condenser 53 are varied according to the nature'of the condensates desired but, in general, vary from a high temperaturetoward the bottom of the apparatus to a much lower temperature to-l ward the top of the same. The variousfrac;

tional condensates are removed from ther condenser 53 through a pluralityof routlets 56.

The gases leaving the condenser 53 yare drawn through a line 57 through a coil 58 that is immersed in a cooling tank 59 to Va receiver ,60.

Water or culated through the coolin'gtanlr 59 and any condensable tar distillatesnotpreviouslyre l .moved from the gas? are there condensed and-*coll ct in the receiver 60. The unco'n-f. densable gases arefdrawn from-the receiver 60 through a line 62 by ablower 63 and pass e through a line 64 to an extension of the main These may beadmixed with further quantities lof fuel,l gas by opening a valve 65 1n the main 43 and then pass through the extension of the main 43to fuel gas mains 85.

-f denser 53 in series or'parallel How and-.is

thendischarged into a vapor chamber` 66. As the tar flowsthrough the cooling sections 54, it serves'to condense the tar distillates from the gases passing through the condenser;

.53 and is thereby heated sufficiently to cause its dehydration'when it is released into the vapor chamber' 66. y

Regulation of the condensing'v effect may be secured bymeans of fractionating valves 67 that are effective to varyith'e distribution of thevtar throughthe various cooling sections 54. r`When the' heated tar discharges through line 35 intotlie vapor chamber 66, the water and light-oil content of the tar is released in the form of a vapor which passes through a line 68 and a coil 69 that is situated in a cooling tank 7 0 into a receiver 7l that may be'connected through a line'g7 2 to a fanL (not shown). i D.

The .dehydrated tar collecting in the botvotherv cooling medium is cir-5' tomof` the -chamber 66 passes through a drain74 into ythe line 34 and flows into the" distillation apparatus 30.

It will be observed that the uppermost cool-- ing section 54-.of the condenser 53visnotprovided with tar lines. ln place of tar, water may be)v employed as cooling medium here, or air-cooling maybe sufficient.

lVhen producer gas or other gas is to 'be used fuel gas,it is supplied to the main through amain 80, having a valve 8l, and a valve 82 inthe main 26 supplyingthe fuel gas holder 27 is then closed.

The actual temperatures and volumes'of mixed fuel gas and products of combustion willvary somewhat according to the nature of the products obtained, i. e., whether a low yield of distillates and a soft pitch residue, or a high yield of distillates and a hard pitch residue, are to be obtained. Obviously, the amount of tar to be distilled and thetime of contact of the tar withthe hot gases will also affect the results.

Itis preferred,.however, to admix sufficient combustible gas with the products of combustion to reduce the temperatureof the mixed gases to below laboutllOOO F.- When using coal gas, which burns with a lflame temperature of about 3500044000o F., it is found that l2 volumes of'additional coal gas (at a temperature of 609 are required to reduce the temperature of the mixed gases to 1400o F., for every one volume of coal gas burned.

It will be obvious that when the colring retort ovens are to be fired with gas having different/llame characteristics, such for example, as producer gas, blue gas, or blast furnace gas, the proportions of the burned gas and the unburned gas required to produce a f mixed -gas of proper temperature willvary accordingly. However, these proportions may be precalculated with considerable accuracyix [As hereinabove set forth, it is important that the mixed gases coming into contact With the tar beingdistilled contain substantially no free oxygen. This requirement is easily satisfied by constructing the furnace in which the combustion and admixture takes place so that the combustible gas vcomes into contact with the gases of combustion at a temperature above the ignition point of the gas and any free oxygenl remaining in the gases of combustion isconsumed.

' In addition, 'careful regulation of admission of airto the gas burners is desirable, and especially when producer gas or other lean gas is used, the employment of burners of the surface combustion type may be advisable. constructed in such form that a"reverse llame is obtained, i. e., air burning in an atmosphere of gas.`

While formation yof soot may occur when coal 'gas or other gas containinghydroc'ar- Or'the combustion chamber may be bons such as methane and ethane is burned in this Way, any soot formed will be scrubbed out of the gases by the tar being distilled and will not be introduced into fiues of the. colre ovens. Blue gas and producer gas contain practically no hydrocarbons, and substantially no soot will be found in their combustion.

Wvhile the mixed gases, after removal of tar distillates, contain an amount of inerts, such as nitrogen and carbon dioxide which renders them unsaleable for many purposes, the presence 'of these inerts is not deleterious insofar as their use as coke-oven fuel is concerned. ln fact, and especially where highchambered ovens are involved, the presence of inerts may constitute an advantage in modifying the flame characteristics lof the fuel Purifications of the from sulphur compounds may be resorted to when necessary. Coal gas contains hydrogen sulphide, which is not in itself seriously corrosive in effect, but which is converted, upon combustion, to sul.- phur dioxide which is corrosive, especially when in the presence of water. Corrosion may thus be evident in the system and especially in the condensing apparatus.

To eliminate this deleterious effect, the gas to be burned may be purified from sulphur impurities, and the gas used for admixture with the products of combustion may also be purified, especially when conditions are' such that some of this admixed combustible gas is burned.

lt is obvious that since a portion of the fuel gas is burned for the purpose of distilling tar, the total amount of the coal gas withdrawn for fuel purposes, or the total amount of gas supplied from producers or generators, must be increased by a similar amount, in order to supply the necessary. heat to the coke ovens.

1While my process is particularly appli.- cable to a coking retort oven plant, and to the employment of the gases produced therein, it is not limited in application to 4such use. For example, liquid fuels, such asr tar and pitch, or even solid fuels, such as coal and colte, may be burned to give the heat necessary to effect the distillation of the tar, and combustible gas, for example, coal gas is then admixed with the gaseous products of combustion to reduce the temperature of the mixed gas and to insure the absence of free oxygen.

Moreover, my process is not limited toftar as such, but may be applied with equally good results to the distillation of derivatives of tar, such as tar oils, obtained by extracting or distilling the primary tar, and the term tar as used herein is to be construed as including such materials'.

My invention is not limited to the specific examples given herein by way of example, but may be variously practiced, and is to be construed as ofthe scope of the following claims.`

I claim as my invention:

1. The method of carbonizing coal and obtaining pitch therefrom which comprises distilling the coal in a battery of coling retorts, removing coal gases and separating tar therefrom, burning a portion of the coal gas, adding to the products of combustion an additional quantity of the coal gas, subjecting the tar'to contact with the mixture of coal gas and products of combustion whereby the tar is distilled to pitch, cooling the gases to remove tar distillates therefrom, mixing the gases used for distillation of the tar with a portion of the coal gas not so used, and employing the mixture of gases thereby obtained to heat said coking retorts.

2. The method of carbonizing coal and obtaining pitch therefrom vvliich comprises distilling the coal in a battery of coking retorts, removing coal gases and separating tar therefrom, burning a portion of the coal gas, adding to the products of combustion an additional quantity of the coal gas, subjecting n the tar tocontact with the mixture of coal gas and products of combustion whereby the tar is distilled to pitch, cooling the gases to remove tar distillates therefrom and supplying the gases to said battery of coking retorts to heat the same.

3. ln a method of 'distilling tar in which a combustible gas is employed as fuel, `the steps which comprise sejaarating a iiow of said fuel gas into two streams, burning one of saidstreams of fuel gas, commingling the hot products of combustion thereby obtained with the other stream of fuel gas tov produce a mixed gas at a temperature relatively low with respect to the temperature of said combustion and containing substantially no free oxygen, and subjecting the tar to be distilled to contact with said mixed gas.

4. In a method of distilling tar in which a combustible gas is employed as fuel, the steps which comprise separating a flow of said fuel gas into two streams, burning oney of said streams of fuel gas, commingling the hot products of combustion thereby obtained with the other stream of fuel gas to produce a mixed gas at a temperature relatively low with respect to the temperature of said combustion and containing substantially no free oxygen, subjecting the tar to be distilled to contact with said mixed gas, removing said gases andv cooling them to condense tar distillates thereby obtained.

5. Ina method of disti-lling tar in which a combustible gas is employed as fuel, the steps which comprise separating a flow of said fuel gas into two streams, burning one of said streams of fuel gas, commingling the hot products of combustion thereby obtained with the other' stream of fuel gas to produce a mixed gas at a temperature of not more v than about 1400" F. and containing substantially no free oxygen, and vsubjecting thel tar to be distilled to Contact with said mixed In testimony whereof, I have hereunto subscribed my name this 13 day of April, 1928.

JOSEPH BECKER. 

